Medical device components

ABSTRACT

Medical device components, such as tube-shaped catheter components, are disclosed. In some embodiments, a medical device component includes a region that includes a polyamide having a hoop stress ratio of at least about 1.25.

CLAIM OF PRIORITY

This application is a continuation of, and claims priority under 35U.S.C. §120 to, and commonly owned U.S. patent application Ser. No.10/669,059, filed on Sep. 23, 2003 and entitled “Medical DeviceComponents and Processes,” which is a continuation-in-part of, andclaims priority under 35 U.S.C. §120 to, and commonly owned U.S. patentapplication Ser. No. 10/256,612, filed on Sep. 26, 2002 now U.S. Pat.No. 7,323,233, and entitled “Sheath Materials and Processes.” The entirecontents of each of the above-noted applications is incorporated byreference herein.

TECHNICAL FIELD

The invention relates to medical device components, such as tube-shapedcatheter components.

BACKGROUND

Medical device components (e.g., tube-shaped catheter components) areused in a variety of systems.

For example, tube-shaped catheter components can be used in ballooncatheters. Balloon catheters are commonly used in medical procedures. Asan example, in some procedures a balloon catheter is used to open anoccluded lumen, as in angioplasty. As another example, a ballooncatheter can be used to selectively block a passageway. In additionalexamples, a balloon catheter is used in various combinations of theseprocedures. Typically, the procedures include positioning a ballooncatheter within a blood vessel at a location of treatment, and inflatingthe balloon portion of the catheter with an inflation fluid. The balloonis then deflated and the catheter is withdrawn from the body.

As another example, tube-shaped catheter components can be used insystems for delivering medical devices, such as stents or grafts. Themedical devices can be balloon-expandable or self-expanding.

SUMMARY

The invention relates to medical device components, such as tube-shapedcatheter components.

In one aspect, the invention features a method of making a component ofa medical device. The method includes longitudinally stretching atube-shaped article while heating the tube-shaped article andpressurizing an interior of the tube-shaped article to form thecomponent of the medical device.

In another aspect, the invention features a method of making atube-shaped component of a medical device. The method includes heating atube-shaped article while pressurizing an interior of the tube-shapedarticle to form the tube-shaped component of the medical device.

In another aspect, the invention features a component (e.g., a catheter)of a medical device. The component includes a polymer with a tensilestrength of at least about 21,000 psi (e.g., at least about 22,500 psi).

In another aspect, the invention features a tube-shaped portion of acatheter. The tube-shaped portion has a tensile strength of at leastabout 21,000 psi (e.g., at least about 22,500 psi).

In another aspect, the invention features a component (e.g., a catheter)of a medical device. The component includes a polymer with a hoop stressof at least about 3300 psi (e.g., at least about 3500 psi).

In another aspect, the invention features a tube-shaped portion of acatheter. The tube-shaped portion has a hoop stress of at least about3300 psi (e.g., at least about 3500 psi).

In another aspect, the invention features a tube-shaped portion of acatheter. The tube-shaped portion has a load at break ratio of at leastabout 1.25 (e.g., at least about 1.5).

In another aspect, the invention features a component (e.g., a catheter)of a medical device. The component includes a polymer with a load atbreak ratio of at least about 1.25 (e.g., at least about 1.5).

In another aspect, the invention features a component (e.g., a catheter)of a medical device. The component includes a polymer having a hoopstress ratio of at least about 1.25 (e.g., at least about 1.5).

In another aspect, the invention features a tube-shaped portion of acatheter. The tube-shaped portion has a hoop stress ratio of at leastabout 1.25 (e.g., at least about 1.5).

In another aspect, the invention features a component (e.g., a catheter)of a medical device. The component includes a polymer with a post bucklefracture tensile strength of at least about 6500 psi.

In another aspect, the invention features a tube-shaped portion of acatheter. The tube-shaped portion has a post buckle fracture tensilestrength of at least about 6500 psi.

Embodiments can include one or more of the following.

While longitudinally stretching the tube-shaped article and/orpressurizing the interior of the tube-shaped article, the tube-shapedarticle can be heated to a temperature that is at least about 0.85 timesa glass transition temperature of the tube-shaped article.

While longitudinally stretching and/or heating the tube-shaped article,a pressure in the interior of the tube-shaped article can be at leastabout 50 psi.

While longitudinally stretching the tube-shaped article, a longitudinalstrain of the tube-shaped article can be at least about 110%.

The method can further include longitudinally stretching a secondtube-shaped article while heating the second tube-shaped article andpressurizing an interior of the second tube-shaped article to form asecond component of the medical device. The method can also includejoining the two components of the medical device.

The method can further include heating a second tube-shaped articlewhile pressurizing an interior of the second tube-shaped article to forma second tube-shaped component of the medical device. The method canalso include joining the two tube-shaped components of the medicaldevice.

The tube-shaped article and/or the component can include a polymer.

The tube-shaped article can include a first section and a secondsection.

The method can include longitudinally stretching the first section whileheating the first section and pressurizing an interior of the firstsection, without longitudinally stretching the second section.

The method can include heating the first section while pressurizing aninterior of the first section, without radially stretching the secondsection.

The component can be tube-shaped. The component can be a catheter.

The medical device can be a catheter.

The catheter can have, for example, a length of from about 30centimeters to about 180 centimeters, and/or an outer diameter of fromabout 0.020 inch to about 0.180 inch.

The medical device can be a balloon catheter. The balloon catheter caninclude a coronary balloon, an aortic balloon, a peripheral balloon, areperfusion balloon, an endoscopy balloon, a urology balloon, or aneurology balloon.

The medical device can be a catheter that is configured to deliver anendoprosthesis (e.g., a self-expanding stent, a balloon-expandablestent) to a body vessel.

The component can be a hypotube sheath portion of a catheter. Thehypotube sheath portion can have a length of from about 0.100 inch toabout 60 inches and/or an outer diameter of from about 0.015 inch toabout 0.180 inch.

The component can be a midshaft portion of a catheter. The midshaftportion can have a length of from about four centimeters to about 25centimeters, and/or an outer diameter of from about 0.015 inch to about0.180 inch.

The component can be a distal outer portion of a catheter. The distalouter portion can have a length of from about ten centimeters to about40 centimeters, and/or an outer diameter of from about 0.015 inch toabout 0.180 inch.

The component can be a distal inner portion of a catheter. The distalinner portion can have a length of from about ten centimeters to about40 centimeters, and/or an outer diameter of from about 0.015 inch toabout 0.180 inch.

A wall thickness of the component can be less than a wall thickness ofthe tube-shaped article.

An outer diameter of the component can be less than an outer diameter ofthe tube-shaped article.

An inner diameter of the component can be less than an inner diameter ofthe tube-shaped article.

The component, the polymer, and/or the tube-shaped portion can have atensile strength of at least about 21,000 psi (e.g., at least about22,500 psi).

The component, the polymer, and/or the tube-shaped portion can have apost buckle fracture tensile strength of at least about 6500 psi (e.g.,at least about 8000 psi).

The component, the polymer, and/or the tube-shaped portion can have ahoop stress of at least about 3300 psi (e.g., at least about 3500 psi).

The component, the polymer, and/or the tube-shaped portion can have ahoop stress ratio of at least about 1.25 (e.g., at least about 1.5).

The component, the polymer, and/or the tube-shaped portion can have aload at break ratio of at least about 1.25 (e.g., at least about 1.5).

The tube-shaped article can include at least one layer. The at least onelayer can include a polymer.

The tube-shaped article can include at least two layers.

The tube-shaped article can have a first layer including a first polymerand a second layer including a second polymer. The first polymer can bedifferent from the second polymer.

The at least two layers can be coextruded and/or joined by an adhesive.

The component and/or the tube-shaped portion can have a first layer anda second layer, and the first layer can have a different flexibilityfrom the second layer.

Features and advantages are in the description, drawings, and claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of an embodiment of a balloon catheter.

FIG. 2 is a cross-sectional view of an embodiment of a tube-shapedcatheter component.

FIG. 3A is a side view of another embodiment of a balloon catheter.

FIG. 3B is a cross-sectional view of the distal end of the ballooncatheter of FIG. 3A.

FIGS. 4A-4E are cross-sectional views of an embodiment of a process forforming a tube-shaped catheter component.

FIGS. 5A-5E are cross-sectional views of another embodiment of a processfor forming a tube-shaped catheter component.

FIG. 6 is a side view of an embodiment of a process for forming atube-shaped catheter component.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of a balloon catheter 100 having aproximal end 110, which generally remains outside the body, and a distalend 120. A manifold 130 is connected to the balloon catheter at proximalend 110. Balloon catheter 100 further includes a sheath 140 havingproximal end 142 and distal end 144, a midshaft 150 having a proximalend 152 and a distal end 154, a hypotube 160 having a proximal end 162and a distal end 164, a distal outer 170 having a proximal end 172, adistal inner 180, and a balloon 175. Sheath 140 surrounds and is bondedto a portion of hypotube 160. Sheath 140 is also bonded to midshaft 150,and midshaft 150 is also bonded to distal outer 170. Balloon cathetershaving this general configuration are known. Examples of suchcommercially available balloon catheters include the Monorail™ family ofballoon catheters (Boston Scientific-SciMed, Maple Grove, Minn.).

Typically, balloon catheter 100 is used as follows. An operator ofballoon catheter 100 delivers distal end 120 of balloon catheter 100into a body lumen (e.g., a blood vessel) over a guidewire. Ballooncatheter 100 is threaded through the lumen to position balloon 175 atthe site of an occlusion. Once balloon 175 reaches the occlusion,balloon 175 is inflated with inflation fluid, so that balloon 175presses against the occlusion. Thereafter, balloon 175 is deflated andremoved from the lumen. Alternatively or additionally, balloon 175 canbe used to deliver a medical device (e.g., a stent, a graft) and/or toblock a passageway.

Manifold 130 is generally designed to control the delivery of inflationfluid to balloon 175, and to control the positioning of distal end 120of balloon catheter 100 in a lumen.

In general, hypotube 160 is designed to act as a part of the conduit forthe inflation fluid and to impart an appropriate amount of stiffness toballoon catheter 100 so that balloon catheter 100 can be positioned(e.g., in a blood vessel) within a patient. Hypotube 160 is typicallymade of a metal or an alloy, although in some cases hypotubes can bemade of a polymer (e.g., one or more of the polymers discussed below).Examples of alloy hypotube materials include nitinol and stainless steel(e.g., 303, 304, 316L).

Generally, sheath 140 is designed to reinforce hypotube 160. Sheath 140typically is formed of a material that is relatively thin and/orrelatively strong (e.g., a material having a relatively high tensilestrength and/or a relatively high hoop stress). Sheath 140 can beformed, for example, of a polymer (e.g., one or more of the polymersdiscussed below).

Midshaft 150 is generally designed to act as an additional portion ofthe conduit for the inflation fluid, and to provide balloon catheter 100with a region of intermediate flexibility. Midshaft 150 is typicallymade of a material that is softer and/or more flexible than the materialfrom which hypotube 160 is formed. Typically, midshaft 150 has a Shore Dhardness of about 72 or more. Midshaft 150 can be formed, for example,of a polymer (e.g., one or more of the polymers discussed below).

Generally, distal outer 170 is designed to act as an additional portionof the conduit for the inflation fluid. Distal outer 170 is typicallymade of a material that is softer and/or more flexible than the materialfrom which midshaft 150 is formed. Typically, distal outer 170 has aShore D hardness of about 70 or less. Distal outer 170 can be formed,for example, of a polymer (e.g., one or more of the polymers discussedbelow).

Distal inner 180 is generally designed to house a guidewire. In someembodiments, distal inner 180 is made of a material that is harder thanthe material from which distal outer 170 is formed, while in otherembodiments distal inner 180 is made of a material that is softer thanthe material from which distal outer 170 is formed. The Shore D hardnessof distal inner 180 can be less than, the same as, or more than theShore D hardness of distal outer 170. Distal inner 180 generally isstrong enough to withstand pressure from inflation fluid. Distal inner180 can be formed, for example, of a polymer (e.g., one or more of thepolymers discussed below).

The guidewire is typically formed of a metal or alloy and is used toprovide the appropriate amount of stiffness to balloon catheter 100while it is being positioned within a body lumen. A portion of theguidewire is disposed within distal inner 180, and a portion of theguidewire is disposed along the outer surface of midshaft 150 and sheath140 (e.g., so that this portion of the guidewire is disposed inside of aguide catheter surrounding distal end 120 of balloon catheter 100).

Balloon 175 can be made of any material appropriate for use in theballoon of a balloon catheter. Typically, balloon 175 is made of one ormore layers of polymeric materials. Typical polymeric materials includepolyesters and polyamides. Exemplary materials are disclosed, forexample, in U.S. Published Patent Application No. US 2002/0165523 A1,published on Nov. 7, 2002, and entitled “Multilayer Medical Device,”which is hereby incorporated by reference.

Referring to FIG 2, a tube-shaped catheter component (e.g., sheath 140,hypotube 160, midshaft 150, distal outer 170, or distal inner 180) hasan inner radius (R_(i)), an outer radius (R_(o)), and a wall thickness(R_(o)−R_(i)).

The tube-shaped catheter component can be used in any of a number ofdifferent applications including, for example, coronary (e.g., 0.014inch wire systems), peripheral (e.g., 0.018 inch wire systems, 0.035inch wire systems), neural, urology, and/or AAA (abdominal aorticaneurysm) applications. In some embodiments, the tube-shaped cathetercomponent can be used as an introducer sheath. The tube-shaped cathetercomponent can be used, for example, in any application in which it maybe desirable to have a strong, thin-walled catheter component.

In general, the inner diameter, outer diameter, and wall thickness ofthe tube-shaped catheter component (e.g., sheath 140, hypotube 160,midshaft 150, distal outer 170, distal inner 180) can be varied asdesired. In some embodiments, however, it may be desirable for thetube-shaped catheter component to be relatively thin because, forexample, this can reduce the profile of the device. For example (e.g.,in 0.014 inch wire systems), the tube-shaped catheter component can havea wall thickness of about 0.005 inch or less (e.g., about 0.004 inch orless, about 0.0035 inch or less, about 0.003 inch or less, about 0.0025inch or less, about 0.002 inch or less, about 0.0015 inch or less, about0.001 inch or less). Typical values for the inner diameter of thetube-shaped catheter component are from about 0.02 inch to about 0.035inch (e.g., from about 0.022 inch to about 0.033 inch), and typicalvalues for the outer diameter of the tube-shaped catheter component arefrom about 0.02 inch to about 0.043 inch (e.g., from about 0.028 inch toabout 0.04 inch).

While the dimensions of hypotube 160 can be varied depending upon theintended use, hypotube 160 usually has an outer diameter of from about0.02 inch to about 0.03 inch (e.g., about 0.0236 inch, about 0.0264inch) and a wall thickness of about 0.003 inch or greater.

In general, sheath 140 can have a wall thickness of about 0.005 inch orless (e.g., about 0.004 inch or less, about 0.0035 inch or less, about0.003 inch or less, about 0.0025 inch or less, about 0.002 inch or less,about 0.0015 inch or less, about 0.001 inch or less). Typical values forthe inner diameter of sheath 140 are from about 0.020 inch to about0.180 inch (e.g., from about 0.020 inch to about 0.030 inch, from about0.022 inch to about 0.0265 inch), and typical values for the outerdiameter of sheath 140 are from about 0.015 inch to about 0.180 inch(e.g., from about 0.025 inch to about 0.035 inch, from about 0.028 inchto about 0.034 inch, from about 0.028 inch to about 0.032 inch). Sheath140 generally has a length from about 0.100 inch to about 60 inches(e.g., about 44 inches).

Midshaft 150 usually has an outer diameter of from about 0.015 inch toabout 0.180 inch (e.g., from about 0.025 inch to about 0.035 inch, fromabout 0.030 inch to about 0.034 inch, about 0.034 inch) and an innerdiameter of from about 0.020 inch to about 0.180 inch (e.g., from about0.020 inch to about 0.030 inch, about 0.0265 inch). Midshaft 150 usuallyhas a wall thickness of about 0.003 inch or less, and/or about 0.001inch or more. In certain embodiments, the inner diameter and/or outerdiameter of midshaft 150 can be tapered. Generally, midshaft 150 has alength from about four centimeters to about 25 centimeters (e.g., aboutten centimeters).

Distal outer 170 generally has an outer diameter from about 0.015 inchto about 0.180 inch (e.g., from about 0.030 inch to about 0.036 inch),and an inner diameter from about 0.020 inch to about 0.180 inch (e.g.,from about 0.020 inch to about 0.040 inch). In some embodiments, theinner and outer diameters of distal outer 170 taper (decrease going fromthe proximal end of distal outer 170 to the distal end of distal outer170). As an example, the proximal end of distal outer 170 can have anouter diameter of 0.0357 inch and an inner diameter of about 0.0283inch, and the distal end of distal outer 170 can have an outer diameterof about 0.0321 inch and an inner diameter of about 0.0263 inch. Incertain embodiments, distal outer 170 is untapered (e.g., with an outerdiameter of from about 0.035 inch to about 0.04 inch, such as about0.037 inch, and an inner diameter of from about 0.0275 inch to about0.0325 inch, such as about 0.0296 inch). Distal outer 170 typically hasa wall thickness of about 0.003 inch or less (e.g., about 0.0027 inch)and/or about 0.001 inch or more. Generally, distal outer 170 has alength from about ten centimeters to about 40 centimeters (e.g., about21.5 centimeters).

Usually, distal inner 180 has an outer diameter of from about 0.015 inchto about 0.180 inch (e.g., from about 0.015 inch to about 0.180 inch,from about 0.020 inch to about 0.024 inch, from about 0.022 inch toabout 0.023 inch), and an inner diameter of from about 0.015 inch toabout 0.023 inch (e.g., from about 0.015 inch to about 0.019 inch, fromabout 0.022 inch to about 0.023 inch). Distal inner 180 typically has awall thickness of about 0.003 inch or less. Generally, distal inner 180has a length of from about ten centimeters to about 40 centimeters(e.g., about 24 centimeters).

Balloon 175 can have a diameter of, for example, at least about onemillimeter (e.g., at least about two millimeters, at least about threemillimeters). In certain embodiments, balloon 175 has a relatively largediameter (e.g., at least about four millimeters, at least about fivemillimeters, at least about six millimeters, at least about sevenmillimeters, at least about eight millimeters, at least about ninemillimeters, at least about 10 millimeters, at least about 11millimeters, at least about 12 millimeters, at least about 20millimeters, at least about 30 millimeters, at least about 40millimeters).

In general, balloon 175 can be of any desired shape and size (e.g., acoronary balloon, an aortic balloon, a peripheral balloon, a reperfusionballoon, an endoscopy balloon, a urology balloon, and a neurologyballoon). In certain embodiments, a coronary balloon can have a diameterof from about 1.5 millimeters to about six millimeters. In someembodiments, a peripheral balloon can have a diameter of from aboutthree millimeters to about 12 millimeters. In certain embodiments, anendoscopy and/or urology balloon can have a diameter of from about fourmillimeters to about 40 millimeters. In some embodiments, a neurologyballoon can have a diameter of from about 1.5 millimeters to about fivemillimeters.

The strength of the tube-shaped catheter component (e.g., sheath 140,hypotube 160, midshaft 150, distal outer 170, distal inner 180) cangenerally be varied as desired. But, in certain embodiments, it can bedesirable for a tube-shaped catheter component to be relatively strong(e.g., strong enough to withstand the inflation fluid pressure). In someembodiments, it can be desirable for sheath 140 to be strong becausethis can enhance the ability of sheath 140 to reinforce hypotube 160.Parameters that can be used to measure the strength of a tube-shapedcatheter component include, for example, load at break, tensile strengthand hoop stress.

In general, the load at break of the tube-shaped catheter component(e.g., sheath 140, hypotube 160, midshaft 150, distal outer 170, distalinner 180) can be varied as desired. Typically, the load at break forthe tube-shaped catheter component is at least about two pounds (e.g.,at least about three pounds, from about three pounds to about fivepounds, from about three pounds to about four pounds). As referred toherein, the load at break of a tube-shaped catheter component isdetermined as follows. The tube-shaped catheter component is bonded(e.g., heat shrunk) to a wire (e.g., a copper wire with a silvercoating), and a longitudinal strain is applied to the wire to reduce thediameter of the wire, thereby removing the tube-shaped cathetercomponent from the wire. Opposite ends of an about three inch longsample of the removed tube-shaped catheter component are placed in gripsthat are about two inches apart from each other. The grips are pulledapart at a strain rate of about three inches per minute until thetube-shaped catheter component breaks, and the load on the sample as thetube-shaped catheter component breaks is the load at break.

In certain embodiments, the tube-shaped catheter component (e.g., sheath140, hypotube 160, midshaft 150, distal, outer 170, distal inner 180)has a tensile strength of at least about 21,000 pounds per square inch(psi) (e.g., at least about 22,500 psi, at least about 25,000 psi, atleast about 27,500 psi, at least about 30,000 psi). As referred toherein, the tensile strength of a tube-shaped catheter component isdetermined by dividing the load at break of the tube-shaped cathetercomponent by the cross-sectional area of the tube-shaped cathetercomponent, where the cross-sectional area of the tube-shaped cathetercomponent is equal to π(R_(o) ²−R_(i) ²).

In certain embodiments, the tube-shaped catheter component (e.g., sheath140, hypotube 160, midshaft 150, distal outer 170, distal inner 180) hasa hoop stress of at least about 3300 psi (e.g., at least about 3500 psi,at least about 3750 psi, at least about 4000 psi, at least about 4250psi, at least about 4500 psi, at least about 4750 psi, at least about5000 psi). As referred to herein, the hoop stress of a tube-shapedcatheter component is equal to P(R_(i) ²+R_(o) ²)/(R_(o) ²−R_(i) ²),where P is the burst pressure of the tube-shaped catheter component.

In general, the burst pressure of the tube-shaped catheter component(e.g., sheath 140, hypotube 160, midshaft 150, distal outer 170, distalinner 180) can be varied as desired. Typically, the tube-shaped cathetercomponent has a burst pressure of at least about 300 psi (e.g., at leastabout 400 psi, from about 400 psi to about 700 psi, from about 500 psito 600 psi). As referred to herein, the burst pressure of a tube-shapedcatheter component refers to the internal pressure at which thetube-shaped catheter component bursts. The burst pressure of atube-shaped catheter component is determined by measuring the internalpressure of the tube-shaped catheter component as the tube-shapedcatheter component (in the case of a hypotube sheath, after beingremoved from the hypotube) is inflated at a rate of two psi per secondwith a 10 second hold at every 50 psi interval until the tube-shapedcatheter component bursts.

The burst diameter (D_(burst)) of the tube-shaped catheter component(e.g., sheath 140, hypotube 160, midshaft 150, distal outer 170, distalinner 180) can also be varied as desired. In certain embodiments, thetube-shaped catheter component has a burst diameter of at least about0.02 inch (e.g. at least about 0.025 inch, at least about 0.03 inch). Asreferred to herein, the burst diameter of a tube-shaped cathetercomponent is the outer diameter of the tube-shaped catheter component atburst. The burst diameter of a tube-shaped catheter component isdetermined by measuring the diameter of the tube-shaped cathetercomponent as the tube-shaped catheter component is inflated at a rate oftwo psi per second with a 10 second hold at every 50 psi interval untilthe tube-shaped catheter component bursts. The diameter is measuredusing a hand held micrometer snap gauge during the 10 second holdperiods.

In some embodiments, the change in distention of the tube-shapedcatheter component (e.g., sheath 140, hypotube 160, midshaft 150, distalouter 170, distal inner 180) is less than about 0.003 inch (e.g., lessthan about 0.002 inch, from about 0.001 inch to about 0.002 inch). Asreferred to herein, the change in distention of a tube-shaped cathetercomponent is equal to D_(burst)-D_(initial), where D_(initial) is theouter diameter of the tube-shaped catheter component prior to inflation.

In some embodiments, the tube-shaped catheter component (e.g., sheath140, hypotube 160, midshaft 150, distal outer 170, distal inner 180) canhave certain additional properties. For example, in certain embodiments,the tube-shaped catheter component has a post buckle fracture tensilestrength of at least about 6500 psi (e.g., at least about 7000 psi, atleast about 7500 psi, at least about 8000 psi). As referred to herein,the post buckle fracture tensile strength of a tube-shaped cathetercomponent is determined by dividing the post buckle fracture load atbreak of the tube-shaped catheter component by the cross-sectional areaof the tube-shaped catheter component, where the cross-sectional area ofthe tube-shaped catheter component is equal to π(R_(o) ²−R_(i) ²).

In general, the post buckle fracture load at break of the tube-shapedcatheter component (e.g., sheath 140, hypotube 160, midshaft 150, distalouter 170, distal inner 180) can be varied as desired. Typically, thepost buckle fracture load at break for the tube-shaped cathetercomponent is at least about one pound (e.g., at least about two pounds,from about two pounds to about five pounds, from about two pounds toabout four pounds). As referred to herein, the post buckle fracture loadat break of a tube-shaped catheter component is determined as follows.Opposite ends of a sample having a length of about 3.5 inches and formedof the tube-shaped catheter component bonded to a hypotube are placed ingrips that are about two inches apart from each other. The grips arecompressed until the distance between the grips is about 0.3 inch at arate of about six inches per minute to buckle the sample. The buckledsample is removed from the grips and straightened so that the hypotubeis broken in two separate pieces with each piece of the hypotube stillbeing bonded to the tube-shaped catheter component. Opposite ends of thesample are placed in the grips (two inches apart) and pulled apart at astrain rate of about three inches per minute until the tube-shapedcatheter component breaks. The load on the sample as the tube-shapedcatheter component breaks is the post buckle fracture load at break.

Typically, the tube-shaped catheter component (e.g., sheath 140,hypotube 160, midshaft 150, distal outer 170, distal inner 180) isformed of a polymer, such as a thermoplastic elastomer (e.g., a heatshrinkable polymer). Examples of polymers include polyamides (e.g.,nylons), copolymers of polyamides (e.g., nylon-polyether copolymers),polyesters (e.g., polyethylene terephthalate (PET) polymers,polybutylene terephthalate (PBT) polymers), copolymers of polyesters,polyetheretherketones (PEEKs), polyurethanes, polyethylenes,polypropylenes, copolymers and ionomers of ethylene, copolymers andionomers of polypropylene, polystyrenes and copolymers of polystyrenes.Examples of commercially available polyesters include the Selar PTfamily of polymers (e.g., Selar PT 8307, Selar PT4274, Selar PTX280),which are commercially available from E. I. DuPont de Nemours(Wilmington, Del.), the Cleartuf family of polymers (e.g., Cleartuf8006), which are commercially available from M&G Polymers (Apple Grove,W.Va.), the Traytuf family of polymers (e.g., Traytuf 1006), which arecommercially available from the Shell Chemical (Houston, Tex.), theMelinar family of polymers, commercially available from E. I. DuPont deNemours (Wilmington, Del.), the Celanex family of polymers, commerciallyavailable from Ticona (Summit, N.J.), the Riteflex family of polymers,commercially available from Ticona (Summit, N.J.), the Hytrel family ofpolymers (e.g., Hytrel 5556, Hytrel 7246, Hytrel 4056), commerciallyavailable from E. I. DuPont de Nemours (Wilmington, Del.), the Arnitelfamily of polymers (e.g., Arnitel EM630), commercially available fromDSM (Erionspilla, Ind.). Examples of commercially available polyamidesinclude Nylon 12, commercially available from Atofina (Philadelphia,Pa.), Nylon 6, commercially available from Honeywell (Morristown, N.J.),Nylon 6/10, commercially available from BASF (Mount Olive, N.J.), Nylon6/12, commercially available from Ashley Polymers (Cranford, N.J.),Nylon 11, Nylon MXD-6, and the Grivory family of polymers, commerciallyavailable from EMS (Sumter, S.C.), the Grilamid® family of polymers(e.g., Grilamid L25, Grilamid L20), commercially available from EMS(Sumter, S.C.), the Vestamid family of polymers (e.g., Vestamid L2101F),commercially available from Daicel-Degussa Ltd., and the PEBAX® familyof polymers (e.g., PEBAX 5533, PEBAX 2533, PEBAX 7033), commerciallyavailable from Atofina (Philadelphia, Pa.), the Trogamid family ofpolyamides from Daicel-Degussa, Cristamid MS 1100 from Atofina(Philadelphia, Pa.), and Vestamid L2101F nylon 12 from Degussa AG. Anexample of a commercially available polyethylene is Marlex 4903 highdensity polyethylene from Phillips 66 (Bartlesville, Okla.).

FIGS. 3A and 3B show a cross-sectional view of an alternate embodimentof a balloon catheter 200, commonly referred to as an over-the-wirecatheter. Catheter 200 includes a tip area 202, an inflatable balloon204 having a waist portion 205, and a shaft portion 206 which extends tothe proximal end 208 of the catheter. Shaft portion 206 is attached atits proximal end 207 to a hub assembly 210. Shaft portion 206 includesan outer tube 212 and an inner tube 214 located coaxially within outertube 212. In some embodiments, outer tube 212 is formed of two tubes, aproximal outer tube and a distal outer tube. An annular lumen 215 isdefined between outer tube 212 and inner tube 214. Inner tube 214 runsthe entire length of the catheter and defines a central lumen 220,disposed to receive a guidewire. At its distal end 222, outer tube 212is necked down slightly to mate with waist portion 205. In certainembodiments catheter 200 can include a hypotube as a tube-shapedcatheter component at proximal end 207 of shaft portion 206. Examples ofsuch commercially available balloon catheters include the NC Ranger®family of balloon catheters (Boston Scientific-SciMed, Maple Grove,Minn.).

Generally, outer tube 212 has an outer diameter of from about 0.015 inchto about 0.180 inch (e.g., from about 0.030 inch to about 0.034 inch),and an inner diameter of from about 0.015 inch to about 0.180 inch(e.g., from about 0.015 inch to about 0.060 inch). Usually, the proximalouter tube of outer tube 212 has an outer diameter of from about 0.030inch to about 0.050 inch (e.g., about 0.042 inch) and an inner diameterof from about 0.020 inch to about 0.050 inch (e.g., about 0.035 inch).The proximal end of the distal outer tube of outer tube 212 typicallyhas an outer diameter of from about 0.030 inch to about 0.060 inch(e.g., about 0.043 inch) and an inner diameter of from about 0.020 inchto about 0.060 inch (e.g., about 0.037 inch). The distal end of thedistal outer tube of outer tube 212 typically has an outer diameter offrom about 0.020 inch to about 0.060 inch (e.g., about 0.037 inch) andan inner diameter of from about 0.020 inch to about 0.050 inch (e.g.,about 0.032 inch). Outer tube 212 usually has a wall thickness of about0.040 inch or less, and about 0.001 inch or more (e.g., about 0.003inch). Generally, outer tube 212 has a length of from about 30centimeters to about 180 centimeters (e.g., about 100 centimeters).

Inner tube 214 typically has an outer diameter of from about 0.015 inchto about 0.180 inch (e.g., from about 0.020 inch to about 0.024 inch,from about 0.022 inch to about 0.023 inch) and an inner diameter of fromabout 0.015 inch to about 0.180 inch (e.g., from about 0.015 inch toabout 0.023 inch, from about 0.015 inch to about 0.019 inch, from about0.022 inch to about 0.023 inch). Inner tube 214 usually has a wallthickness of about 0.003 inch or less. Generally, inner tube 214 has alength of from about 30 centimeters to about 180 centimeters (e.g.,about 100 centimeters).

A tube-shaped component of catheter 200 (e.g., outer tube 212, innertube 214) generally can have the properties (e.g., load at break,tensile strength, hoop stress, burst pressure, burst diameter, change indistention, post buckle fracture tensile strength, and/or post bucklefracture load at break) noted above, and/or can be formed from thematerials noted above.

A tube-shaped catheter component (e.g., sheath 140, hypotube 160,midshaft 150, distal outer 170, distal inner 180, outer tube 212, innertube 214) can be formed of one layer of material (e.g., a polymer), orof multiple layers of material (e.g., at least two layers, at leastthree layers, at least four layers, at least five layers, at least sixlayers, at least seven layers, at least eight layers, at least ninelayers, at least ten layers). In some embodiments in which thetube-shaped catheter component is formed of multiple layers of material,the tube-shaped catheter component can have increased strength relativeto tube-shaped catheter components formed of one layer of material. Incertain embodiments in which the tube-shaped catheter component isformed of multiple layers of different materials, the tube-shapedcatheter component can exhibit both good strength and good flexibility.

In certain embodiments in which the tube-shaped catheter component(e.g., sheath 140, hypotube 160, midshaft 150, distal outer 170, distalinner 180, outer tube 212, inner tube 214) is formed of multiple layersof material, one of the layers in a pair of adjacent layers can beformed of a certain type (e.g., grade) of a polymer, and the other layerin the pair can be formed of a different type (e.g., grade) of the samepolymer. As an example, in certain embodiments in which the tube-shapedcatheter component is formed of multiple layers of material, one of thelayers in a pair of adjacent layers can be formed of one type ofpolyester, and the other layer in the pair can be formed of a differenttype of polyester. As another example, in some embodiments in which thetube-shaped catheter component is formed of multiple layers of material,one of the layers in a pair of adjacent layers can be formed of one typeof polyamide, and the other layer in the pair can be formed of adifferent type of polyamide.

In certain embodiments in which the tube-shaped catheter component(e.g., sheath 140, hypotube 160, midshaft 150, distal outer 170, distalinner 180, outer tube 212, inner tube 214) is formed of multiple layersof material, the layers in a pair of adjacent layers are formed ofdifferent polymers. As an example, in some embodiments, one of thelayers in a pair of adjacent layers can be formed of a polyester, andthe other layer in the pair can be formed of a polyamide.

In certain embodiments in which the tube-shaped catheter component(e.g., sheath 140, hypotube 160, midshaft 150, distal outer 170, distalinner 180, outer tube 212, inner tube 214) is formed of multiple layersof material (e.g., two layers, three layers, four layers, five layers,six layers, seven layers, eight layers, nine layers, ten layers), some(e.g., all) of the layers can have different flexibilities. For example,a multilayer tube-shaped catheter component can have an outer layer thatis more flexible than at least one of the inner layers (e.g., all of theinner layers) of the tube-shaped catheter component. In someembodiments, a multilayer tube-shaped catheter component can have anouter layer that is less flexible than at least one of the inner layers(e.g., all of the inner layers) of the tube-shaped catheter component.Flexibility can be measured as flex modulus, which can be calculatedusing a three-point bend test with a one inch gauge length and acrosshead speed of about 0.3 inch per minute. In some cases, amultilayer tube-shaped catheter component can have inner and outerlayers with relatively low flexibilities (e.g., having a flex modulus offrom about 160,000 to about 260,000 psi (e.g., about 200,000 psi),according to the three-point bend test), and a middle layer (between theinner and outer layers) with a relatively high flexibility (e.g., havinga flex modulus of from about 30,000 psi to about 90,000 psi (e.g., about50,000 psi), according to the three-point bend test). In certainembodiments, a multilayer tube-shaped catheter component can have innerand outer layers with relatively high flexibilities (e.g., having a flexmodulus of from about 30,000 psi to about 90,000 psi (e.g., about 50,000psi), according to the three-point bend test), and a layer between theinner and outer layers with a relatively low flexibility (e.g., having aflex modulus of from about 160,000 psi to about 260,000 psi (e.g., about200,000 psi), according to the three-point bend test).

In some embodiments, the layers in a multilayer tube-shaped cathetercomponent (e.g., sheath 140, hypotube 160, midshaft 150, distal outer170, distal inner 180, outer tube 212, inner tube 214) can be extruded(e.g., as separate extrusions or as a coextrusion). Examples ofextrusion processes are described in U.S. Published Patent ApplicationNo. US 2002/0165523 A1. Examples of extrusion processes also aredescribed in co-pending and commonly owned U.S. patent application Ser.No. 10/274,633, filed Oct. 21, 2002 and entitled “Multilayer MedicalDevice”, and co-pending and commonly owned U.S. patent application Ser.No. 10/351,695, filed Jan. 27, 2003 and entitled “Multilayer BalloonCatheter”, both of which are hereby incorporated by reference in theirentirety. In certain embodiments, the layers in a multilayer tube-shapedcatheter component are joined by, for example, an adhesive. In somecases, the layers in a multilayer catheter are joined by an intermediateadhesive layer. Such layers are disclosed in U.S. patent applicationSer. No. 10/351,695.

In general, a tube-shaped catheter component (e.g., sheath 140, hypotube160, midshaft 150, distal outer 170, distal inner 180, outer tube 212,inner tube 214) can be prepared as desired. In some embodiments, atube-shaped catheter component can be prepared by applying heat,internal pressure, and a longitudinal strain to a tube of material. Incertain embodiments, a tube-shaped catheter component can be prepared byapplying heat and internal pressure to a tube of material, withoutapplying a longitudinal strain.

FIGS. 4A-4C show an embodiment of a method for forming a tube-shapedcatheter component (e.g., sheath 140, hypotube 160, midshaft 150, distalouter 170, distal inner 180, outer tube 212, inner tube 214) by applyingheat, internal pressure, and a longitudinal strain to a tube ofmaterial. As shown in FIG. 4A, a tube 300 of material is provided. Forexample, tube 300 can be formed by extrusion. Tube 300 can be formed ofone layer or multiple layers. A longitudinal strain, heat and internalpressure are applied to tube 300. This process is referred to herein aslongitudinally stretch-blowing the tube. FIG. 4B shows an intermediatetube 305 formed part way through the longitudinal stretch-blowingprocess. The longitudinal strain applied to the tube is indicated by thehorizontal arrows, and the internal pressure applied to the tube isindicated by the vertical arrows. The longitudinal strain, pressure andtemperature are ultimately reduced to provide a longitudinallystretch-blown tube 310 of material having an outer diameter that issmaller than the outer diameter of tube 300 and an inner diameter thatis smaller than the inner diameter of tube 300 (FIG. 4C).

In certain embodiments, a hypotube sheath is formed by adding the stepsshown in FIGS. 4D and 4E to the process of FIGS. 4A-4C. Referring toFIGS. 4D and 4E, a hypotube 320 is placed within stretch-blown tube 310(FIG. 4D), and stretch-blown tube 310 is heated so that its innerdiameter decreases, resulting in a sheath 330 of component materialbonded (e.g., heat shrunk) to hypotube 320 (FIG. 4E).

While an embodiment of a process for forming a tube-shaped cathetercomponent (e.g., sheath 140, hypotube 160, midshaft 150, distal outer170, distal inner 180, outer tube 212, inner tube 214) using heat,internal pressure, and longitudinal strain has been described, otherembodiments are possible. In general, the parameters selected during theprocess can be varied as desired. As an example, the parameters (e.g.,longitudinal strain, pressure, temperature) can be selected so thatlongitudinally stretch-blown tube 310 of material has an outer diameterthat is substantially the same as the outer diameter of tube 300 and aninner diameter that is larger than the inner diameter of tube 300. Asanother example, the parameters (e.g., longitudinal strain, pressure,temperature) can be selected so that longitudinally stretch-blown tube310 of material has an outer diameter that is smaller than the outerdiameter of tube 300 and an inner diameter that is substantially thesame as the inner diameter of tube 300.

Without wishing to be bound by theory, it is believed that there aresome general trends that depend upon the values of certain parameters(e.g., longitudinal strain, temperature and pressure) used whenlongitudinally stretch-blowing the tube. The general trends include thefollowing. For a given tube material and desired dimensions for theintermediate tube, increasing the value of one parameter allows for theuse of lower values for one or both of the other parameters. For a givenmaterial, pressure and longitudinal strain, increasing the temperatureresults in an intermediate tube with a larger outer diameter. When thetube-shaped catheter component is a hypotube sheath, the resultingintermediate tube tends to undergo a greater degree of shrinkage duringthe process of bonding (e.g., heat shrinking) to the hypotube. For agiven material, pressure and longitudinal strain, decreasing thetemperature results in an intermediate tube with a smaller outerdiameter. In the case in which the tube-shaped catheter component is ahypotube sheath, the resulting intermediate tube tends to undergo asmaller degree of shrinkage during the process of bonding (e.g., heatshrinking) to the hypotube. For a given material, temperature andpressure, increasing the longitudinal strain results in an intermediatetube with a smaller inner diameter. When the tube-shaped cathetercomponent is a hypotube sheath, the resulting intermediate tube tends toundergo a smaller degree of shrinkage during the process of bonding(e.g., heat shrinking) to the hypotube. For a given material,temperature and pressure, decreasing the longitudinal strain results inan intermediate tube with a larger inner diameter. In the case in whichthe component is a hypotube sheath, the resulting intermediate tubetends to undergo a greater degree of shrinkage during the process ofbonding (e.g., heat shrinking) to the hypotube. For a given material,temperature and longitudinal strain, increasing the pressure results inan intermediate tube with a larger outer diameter. When the tube-shapedcatheter component is a hypotube sheath, the intermediate tube tends toundergo a greater degree of shrinkage during the process of bonding(e.g., heat shrinking) to the hypotube. For a given material,temperature and longitudinal strain, decreasing the pressure results inan intermediate tube with a smaller outer diameter. In the case in whichthe tube-shaped catheter component is a hypotube sheath, theintermediate tube tends to undergo a smaller degree of shrinkage duringthe process of bonding (e.g., heat shrinking) to the hypotube.

When longitudinally stretch-blowing a tube of material, the temperatureof the material should be sufficient to allow the tube to undergo thedesired change in dimensions (e.g., to elongate and/or become thinner).The temperature can be varied from, for example, below the glasstransition temperature of the material (T_(g)) from which the tube isformed up to about 0.9 times the melt temperature (T_(m)) of thematerial from which the tube is formed, where T_(m) is measured inKelvin. For example, the temperature used during longitudinalstretch-blowing can be at least about 0.85T_(g) (e.g., from about0.85T_(g) to about 1.2T_(g), from about 0.85T_(g) to about 1.1T_(g),from about 0.85T_(g) to about T_(g)), where T_(g) is measured in Kelvin.As referred to herein, the glass transition temperature of a material(e.g., a polymer) is determined according to ASTM D1356, and the melttemperature of a material (e.g., a polymer) is determined according toDIN 16770D2. As an example, Vestamid L2101F nylon 12 (Degussa AG) has aT_(g) of about 333K and a T_(m) of about 518K, and a temperature ofabout 318K can be used for this material during longitudinalstretch-blowing, corresponding to about 0.95T_(g) and about 0.6T_(m).

In embodiments in which a tube-shaped catheter component is formed of ablock copolymer material, the glass transition temperature and melttemperature of the material refer to the glass transition temperatureand melt temperature of the block within the block copolymer that hasthe highest glass transition temperature and melt temperature. Forexample, PEBAX 6333 (Atofina) is a block copolymer that contains blocksof nylon 12, and nylon 12 is the block with the highest glass transitiontemperature and melt temperature in PEBAX 6333. Thus, as referred toherein, the glass transition temperature and melt temperature of PEBAX6333 correspond to the glass transition temperature and melt temperatureof the nylon 12 blocks in PEBAX 6333. Accordingly, PEBAX 6333 has aT_(g) of about 333K and a T_(m) of about 445K, and a temperature ofabout 318K can be used for this material during longitudinalstretch-blowing, corresponding to about 0.95T_(g) and about 0.7T_(m).

In embodiments in which the tube-shaped catheter component (e.g., sheath140, hypotube 160, midshaft 150, distal outer 170, distal inner 180,outer tube 212, inner tube 214) is formed of multiple layers and inwhich at least two of the layers are of different materials (e.g., anylon (such as an amorphous nylon, a semiaromatic nylon) and apolyester), the glass transition temperature and melt temperature of thetube-shaped catheter component refer to the glass transition temperatureand melt temperature of the layer of material in the tube-shapedcatheter component that has the highest glass transition temperature andmelt temperature. For those materials (e.g., amorphous materials) thatdo not have a melt temperature, a melt processing temperature(T_(m(process))) is used instead. For example, the glass transitiontemperature and melt processing temperature of a two-layer tube-shapedcatheter component having a layer of PEBAX 6333 and a layer of GrilamidTR55 LX are equal to the glass transition temperature and meltprocessing temperature of the layer with the higher glass transitiontemperature and melt processing temperature (i.e., the glass transitiontemperature (155° C.) and melt processing temperature (240-260° C.) ofGrilamid TR55 LX). Accordingly, a temperature of about 145° C. can beused for the above two-layer tube-shaped catheter component duringlongitudinal stretch-blowing, corresponding to about 0.98T_(g) and about0.8T_(m(process)).

In certain embodiments, the temperature of the material duringlongitudinal stretch-blowing is not measured directly. For example,during longitudinal stretch-blowing, the material may be present in anoven for a period of time. The temperature of the material can beinferred from the period of time the material spent in the oven and thephysical characteristics (e.g., heat capacity, thermal conductivity) ofthe material. The temperature of the material can also be inferred bycomparing the properties of the longitudinally stretch-blown material tothose of the longitudinally stretch-blown material achieved underconditions where the temperature of the material during longitudinalstretch-blowing is known. For example, the temperature can be inferredby comparing the properties of a longitudinally stretch-blown materialto those of the longitudinally stretch-blown material achieved when thematerial is held in a constant temperature bath (e.g., constanttemperature water bath) during longitudinal stretch-blowing.

The longitudinal strain applied to the tube when longitudinallystretch-blowing the tube should be sufficient to allow the material fromwhich the tube is made to undergo the desired change in dimensions(e.g., to elongate and/or become thinner). Typically, the longitudinalstrain is at least about 110% (e.g., at least about 120%, at least about130%, at least about 140%, at least about 150%, at least about 170%, atleast about 200%, at least about 210%, at least about 230%, at leastabout 260%, at least about 290%, at least about 320%, at least about350%), where the percent longitudinal strain corresponds to the increasein the length of the tube due to longitudinally stretch-blowing thetube. For example, 150% longitudinal strain refers to the stretch-blowntube having a length that is 1.5 times the length the tube had justbefore being longitudinally stretch-blown.

The internal pressure of the tube during longitudinal stretch-blowingshould be sufficient for the material from which the tube is made toundergo the desired change in dimensions (e.g., to elongate and/orbecome thinner). Typically, the internal pressure is at least about 50psi (e.g., at least about 75 psi, at least about 100 psi, at least about125 psi, at least about 150 psi).

FIGS. 5A-5C show an alternate embodiment for forming a tube-shapedcatheter component, in which a tube is pressurized and heated withoutapplying a longitudinal strain. As shown in FIG. 5A, a tube 400 ofmaterial is provided. For example, tube 400 can be formed by extrusion.Pressure and heat are applied to tube 400, without applying alongitudinal strain. This process is referred to herein as radiallystretch-blowing the tube. FIG. 5B shows an intermediate tube 405 formedpart way through the radial stretch-blowing process, in which thepressure applied to the tube is indicated by arrows. The pressure andtemperature are ultimately reduced to provide a radially stretch-blowntube 410 of material having an outer diameter that is larger than theouter diameter of tube 400, an inner diameter that is larger than theinner diameter of tube 400, and a wall thickness that is smaller thanthe wall thickness of tube 400 (FIG. 5C).

In certain embodiments, a hypotube sheath is formed by adding the stepsshown in FIGS. 5D and 5E to the process of FIGS. 5A-5C. In FIGS. 5D and5E, a hypotube 420 is placed within radially stretch-blown tube 410(FIG. 5D), and radially stretch-blown tube 410 is heated so that itsinner diameter decreases, resulting in a sheath 430 of material bonded(e.g., heat shrunk) to hypotube 420 (FIG. 5E).

When radially stretch-blowing a tube of material, the temperature of thematerial should be sufficient to allow the tube to undergo the desiredchange in dimensions (e.g., to expand in diameter and/or becomethinner). The temperature can be varied from, for example, below theglass transition temperature of the material (T_(g)) from which the tubeis formed up to about 0.9 times the melt temperature (T_(m)) of thematerial from which the tube is formed, where T_(m) is measured inKelvin. For example, the temperature used during radial stretch-blowingcan be at least about 0.85T_(g) (e.g., from about 0.85T_(g) to about1.2T_(g), from about 0.85T_(g) to about 1.1T_(g), from about 0.85T_(g)to about T_(g)), where T_(g) is measured in Kelvin.

In certain embodiments, the temperature of the material during radialstretch-blowing is not measured directly. For example, during radialstretch-blowing, the material may be present in an oven for a period oftime. The temperature of the material can be inferred from the period oftime the material spent in the oven and the physical characteristics(e.g., heat capacity, thermal conductivity) of the material. Thetemperature of the material can also be inferred by comparing theproperties of the radially stretch-blown material to those of theradially stretch-blown material achieved under conditions where thetemperature of the material during radial stretch-blowing is known. Forexample, the temperature can be inferred by comparing the properties ofa radially stretch-blown material to those of the radially stretch-blownmaterial achieved when the material is held in a constant temperaturebath (e.g., constant temperature water bath) during radialstretch-blowing.

When radially stretch-blowing a tube of material, the internal pressureof the tube should be sufficient for the material from which the tube ismade to undergo the desired change in dimensions (e.g., to expand indiameter and/or to become thinner). Typically, the internal pressure isat least about 50 psi (e.g., at least about 75 psi, at least about 100psi, at least about 125 psi, at least about 150 psi).

In some embodiments, individual tube-shaped catheter components areformed (e.g., using the methods discussed above), and then are attachedto each other. For example, a first tube-shaped catheter component(e.g., a midshaft) can be formed by longitudinal stretch-blowing, andcan be joined to a second tube-shaped catheter component (e.g., a distalouter) which has been formed by radial stretch-blowing. In some cases, afirst tube-shaped catheter component (e.g., a hypotube sheath) is formedby longitudinal stretch-blowing, and is joined to a second tube-shapedcatheter component (e.g., a midshaft) which has also been formed bylongitudinal stretch-blowing. In certain embodiments, a firsttube-shaped catheter component (e.g., a distal outer) is formed byradial stretch-blowing, and is joined to a second tube-shaped cathetercomponent (e.g., a midshaft) which has also been formed by radialstretch-blowing. In some embodiments, a first tube-shaped cathetercomponent is formed by longitudinal or radial stretch-blowing, and isjoined to a second tube-shaped catheter component which has not beenformed by either longitudinal or radial stretch-blowing.

The first and second tube-shaped catheter components can be made of thesame or of different materials. For example, the first tube-shapedcatheter component can include polyethylene terephthalate andpolybutylene terephthalate, and/or polyethylene terephthalate andHytrel®. As another example, the first tube-shaped catheter componentcan be made of a nylon (e.g., nylon-12, Grilamid TR55, Cristamid® MS1100), while the second tube-shaped catheter component can be made of apolyester (e.g., PEBAX®). As another example, the first tube-shapedcatheter component can include a polyamid and a polyamid copolymer,and/or a polyester and a polyester copolymer. The first and secondtube-shaped catheter components can both be single-layer tube-shapedcatheter components or can both be multilayer tube-shaped cathetercomponents. The first tube-shaped catheter component can be formed ofone layer, while the second tube-shaped catheter component can be amultilayer tube-shaped catheter component.

The first and second tube-shaped catheter components can exhibitdifferent properties. The first and second tube-shaped cathetercomponents can have different flexibilities. For example, the firsttube-shaped catheter component can have a flexibility of about 30,000psi to about 90,000 psi (e.g., about 50,000 psi), while the secondtube-shaped catheter component can have a flexibility of about 160,000psi to about 260,000 psi (e.g., about 200,000 psi).

In certain embodiments, the first and second tube-shaped cathetercomponents are joined by a butt or lap welding process. In someembodiments, the first and second tube-shaped catheter components arejoined by an adhesive (e.g., urethane).

In certain embodiments, a tube-shaped catheter component is formed bylongitudinally or radially stretch-blowing a portion of a tube ofmaterial. For example, and referring now to FIG. 6, a fixture 400 (e.g.,a clamp) is used to hold a first portion 402 of a tube 404 of materialin a stationary position. Thereafter, a second portion 406 of tube 404can be longitudinally or radially stretch-blown. (In FIG. 6, secondportion 406 is longitudinally stretch-blown, the longitudinal strainbeing depicted with arrows.) The stationary portion of the tube isgenerally unaffected by the stretch-blowing process. A transition region408 between stationary first portion 402 and stretch-blown secondportion 406 experiences an intermediate amount of stretching during thestretch-blowing process.

In some embodiments, a bump extrusion is formed on a tube of material.The portion of the tube including the bump extrusion can then belongitudinally or radially stretch-blown while another portion of thetube is held stationary and is generally unaffected by thestretch-blowing process.

In certain embodiments, an extrusion process can be structured to form atube of material having the same dimensions (e.g., outer diameter, innerdiameter), but a variable polymer orientation, along its length.Thereafter, the tube can be longitudinally or radially stretch-blown.The product of stretch-blowing can be a tube with variable flexibilityand strength along its length.

Without wishing to be bound by theory, it is believed that thelongitudinal and radial stretch-blowing processes described herein canresult in a relatively strong tube-shaped catheter component. Inparticular, it is believed that the use of a longitudinal strain and/orpressure during the stretch-blowing portion of the process ultimatelyresults in a tube-shaped catheter component that is relatively thin, butthat has, for example, a burst pressure and/or load at break that iscomparable to those achieved by tube-shaped catheter componentpreparation processes that result in relatively thick tube-shapedcatheter components (e.g., processes in which a longitudinal strainand/or pressure is not used). It is believed that longitudinal andradial stretch-blowing result in relatively thin tube-shaped cathetercomponents that have relatively large tensile strengths and/orrelatively large hoop stresses.

As an example, a catheter component material can have a tensile strengthratio of at least about 1.25 (e.g., at least about 1.5, at least about1.75, at least about two, at least about 2.25). As used herein thetensile strength ratio of a catheter component material is determined bydividing the tensile strength of the material as a tube-shaped cathetercomponent (according to one or more of the procedures described above)by the tensile strength of the material before being longitudinally orradially stretch-blown (e.g., as an extruded tube).

As another example, a catheter component material can have a hoop stressratio of at least about 1.25 (e.g., at least about 1.5, at least abouttwo, at least about 2.5, at least about three). As used herein, the hoopstress ratio of a catheter component material is determined by dividingthe hoop stress of the material as a tube-shaped catheter component(according to the procedure described above) by the hoop stress of thematerial before being longitudinally or radially stretch-blown (e.g., asan extruded tube).

Without wishing to be bound by theory, it is further believed that theprocess described herein for bonding a hypotube sheath to a hypotube canresult in a hypotube sheath having a polymer chain profile in which thepolymer chains are substantially axially oriented (e.g., with the degreeof axial orientation generally increasing from the outer radius of thehypotube sheath to the inner radius of the hypotube sheath).

The following examples are illustrative and not intended to be limiting.

EXAMPLES

Tables I and II list average values for certain parameters determinedfor multiple specimens of different hypotube/hypotube sheath samples.“O.D.” refers to the average outer diameter of the hypotube sheaths ofthe corresponding specimens in units of inches. “I.D.” refers to theaverage inner diameter of the hypotube sheaths of the correspondingspecimens in units of inches. “Thickness” refers to the average wallthickness [(outer diameter minus inner diameter)/2] of the hypotubesheaths of the corresponding specimens in units of inches. “Area”refersto the average cross-sectional area (pi multiplied by the differencebetween the square of the outer radius and the square of the innerradius) of the hypotube sheaths of the corresponding specimens in unitsof square inches. “Post Load” refers to the average post buckle fractureload at break of the hypotube sheaths of the corresponding specimens inunits of pounds. “Post Tensile” refers to the post buckle fractureaverage tensile strength of the hypotube sheaths of the correspondingspecimens units of pounds per square inch. “Load” refers to the load atbreak of the hypotube sheaths of the corresponding specimens in units ofpounds. “Tensile” refers to the average tensile strength of the hypotubesheaths of the corresponding specimens units of pounds per square inch.“Distention” refers to the average change in outer diameter of thehypotube sheaths (outer diameter at burst minus outer diameter prior toinflation) of the corresponding specimens in units of inches.“Diameter”refers to the average burst diameter of the hypotube sheathsof the corresponding specimens in units of inches. “Pressure” refers tothe burst pressure the hypotube sheaths of the corresponding specimensin units of psi. “Stress” refers to the burst stress of the hypotubesheaths of the corresponding samples in units of psi.

TABLE I Post Post Sample O.D. I.D. Thickness Area Load Tensile A 0.03020.022 0.0041 3.362 × 10⁻⁴ 1.37 4075 B 0.028 0.0234 0.0023 1.857 × 10⁻⁴1.200 6462 C 0.0296 0.0264 0.0016 1.407 × 10⁻⁴ 1.920 13642 D 0.03160.0264 0.0026 2.369 × 10⁻⁴ 4.420 18660 E 0.03038 0.02393 0.003225 2.751× 10⁻⁴ 4.850 17628 F 0.02891 0.02394 0.002485 2.063 × 10⁻⁴ 3.794 18391 G0.0294 0.0264 0.0015 1.322 × 10⁻⁴ 1.48 11195

TABLE II Sample O.D. I.D. Thickness Distention Diameter Load TensilePressure Stress H 0.0291 0.0262 0.0015 0.0015 0.0306 3.78 31659 535 5123I 0.0282 0.0236 0.0023 0.0012 0.0247 2.47 15129 572 3197 J 0.0274 0.02320.0021 0.0013 0.0244 3.62 20030 529 3239

Sample A was a Multi-Link Plus™ hypotube (Guidant, Santa Clara, Calif.)modified as follows. A Multi-Link Plus™ hypotube was cut to isolate aspecimen formed from the proximal portion of the device containing onlythe sheath bonded to the hypotube. Three specimens of sample A weretested. The average values of certain parameters determined for thespecimens of sample A are listed in Table I.

Sample B was an AVE S7 hypotube (Medtronic AVE, Santa Rosa, Calif.)modified as follows. An AVE S7 hypotube was cut to isolate a specimenformed from the proximal portion of the device containing only thesheath (PEBAX 7233) bonded to the hypotube. Two specimens of sample Bwere tested. The average values of certain parameters determined for thespecimens of sample B are listed in Table I.

Sample C was prepared as follows. An extruded sheath of Vestamid L2101 FNylon 12 (Degussa AG) having an outer diameter of about 0.0350 inch andan inner diameter of about 0.0276 inch was longitudinally stretch-blownunder a longitudinal strain of 220% and an internal pressure of 208 psi.During longitudinal stretch-blowing, the sheath material passed throughan 18 inch oven at a temperature of about 63° C. over a period of about8.9 seconds. It is believed that the sheath material reached atemperature of about 40° C. to about 45° C. during longitudinalstretch-blowing. A 304L stainless steel hypotube having an outerdiameter of about 0.0264 inch and an inner diameter of about 0.020 inchwas inserted inside the longitudinally stretched and blown sheath, andthe sheath was bonded (heat shrunk) to the hypotube by heating to atemperature of about 113° C. for at least 30 minutes. Ten specimens ofsample C were tested, and the average values of certain parametersdetermined for the specimens of sample C are listed in Table I.

Sample D was prepared as follows. An extruded sheath of Vestamid L2101 FNylon 12 (Degussa AG) having an outer diameter of about 0.0380 inch andan inner diameter of about 0.0270 inch was longitudinally stretch-blownunder a longitudinal strain of 190% and an internal pressure of 288 psi.During longitudinal stretch-blowing, the sheath material passed throughan 18 inch oven at a temperature of about 68° C. over a period of about17.1 seconds. It is believed that the sheath material reached atemperature of about 40° C. to about 45° C. during longitudinalstretch-blowing. A 304L stainless steel hypotube having an outerdiameter of about 0.0264 inch and an inner diameter of about 0.020 inchwas inserted inside the longitudinally stretched and blown sheath, andthe sheath was bonded (heat shrunk) to the hypotube by heating to atemperature of about 113° C. for at least about 30 minutes. Fivespecimens of sample D were tested, and the average values of certainparameters determined for the specimens of sample D are listed in TableI.

Sample E was prepared as follows. An extruded sheath of PEBAX 7233(Atofina) having an outer diameter of about 0.035 inch and an innerdiameter of about 0.024 inch was longitudinally stretch-blown under alongitudinal strain of 150% and an internal pressure of 278 psi. Duringlongitudinal stretch-blowing, the sheath material passed through an 18inch oven at a temperature of about 68° C. over a period of about 19.5seconds. It is believed that the sheath material reached a temperatureof about 40° C. to about 45° C. during longitudinal stretch-blowing. A304L stainless steel hypotube having an outer diameter of about 0.0237inch and an inner diameter of about 0.0175 inch was inserted inside thelongitudinally stretched and blown sheath, and the sheath was bonded(heat shrunk) to the hypotube by heating to a temperature of about 113°C. for at least about 30 minutes. Five specimens of sample E weretested, the average values of certain parameters determined for thespecimens of sample E are listed in Table I.

Sample F was prepared as follows. An extruded sheath of 95% VestamidL2101 F Nylon 12 (Degussa AG)/5% PEBAX 7233 (Atofina) having an outerdiameter of about 0.0340 inch and an inner diameter of about 0.0240 inchwas longitudinally stretch-blown under a longitudinal strain of 150% andan internal pressure of 268 psi. During longitudinal stretch-blowing,the sheath material passed through an 18 inch oven at a temperature ofabout 68° C. over a period of about 19.5 seconds. It is believed thatthe sheath material reached a temperature of about 40° C. to about 45°C. during longitudinal stretch-blowing. A 304L stainless steel hypotubehaving an outer diameter of about 0.0237 inch and an inner diameter ofabout 0.0175 inch was inserted inside the longitudinally stretched andblown sheath, and the sheath was bonded (heat shrunk) to the hypotube byheating to a temperature of about 113° C. for about 30 minutes. Fivespecimens of sample F were tested, and the average values of certainparameters determined for the specimens of sample F are listed in TableI.

Sample G was prepared as follows. An extruded sheath of PEBAX 6333(Atofina) having an outer diameter of about 0.034 inch and an innerdiameter of about 0.0280 inch was longitudinally stretched and blownunder a longitudinal strain of 155% and an internal pressure of 145 psi.During longitudinal stretch-blowing, the sheath material passed throughan 18 inch oven at a temperature of about 68° C. over a period of about18.9 seconds. It is believed that the sheath material reached atemperature of about 40° C. to about 45° C. during longitudinalstretch-blowing. A 304L stainless steel hypotube having an outerdiameter of about 0.0264 inch and an inner diameter of about 0.020 inchwas inserted inside the longitudinally stretched and blown sheath, andthe sheath was bonded (heat shrunk) to the hypotube by heating to atemperature of about 113° C. for at least about 30 minutes. Fivespecimens of sample G were tested, and the average values of certainparameters determined for the specimens of sample G are listed in TableI.

Sample H was prepared as follows. An extruded sheath of Vestamid L2101 FNylon 12 (Degussa AG) having an outer diameter of about 0.0380 inch andan inner diameter of about 0.0320 inch was longitudinally stretched andblown under a longitudinal strain of 220% and an internal pressure of142 psi. During longitudinal stretch-blowing, the sheath material passedthrough an 18 inch oven at a temperature of about 63° C. over a periodof about 8.9 seconds. It is believed that the sheath material reached atemperature of about 40° C. to about 45° C. during longitudinalstretch-blowing. A 304L stainless steel hypotube having an outerdiameter of about 0.0264 inch and an inner diameter of about 0.0200 inchwas inserted inside the longitudinally stretched and blown sheath, andthe sheath was bonded (heat shrunk) to the hypotube by heating to atemperature of about 113° C. for at least about 30 minutes. Fivespecimens of sample H were tested, and the average values of certainparameters determined for the specimens of sample H are listed in TableII.

Sample I was a Multi-Link Plus™ hypotube (Guidant, Santa Clara, Calif.)modified as follows. A Multi-Link Plus™ hypotube was cut to isolate aspecimen formed from the proximal portion of the device containing onlythe sheath bonded to the hypotube. 10 specimens of sample A were tested.Three specimens of sample I were tested. The average values of certainparameters determined for the specimens of sample I are listed in TableII.

Sample J was AVE S7 hypotube (Medtronic AVE, Santa Rosa, Calif.)modified as follows. An AVE S7 hypotube was cut to isolate a specimenformed from the proximal portion of the device containing only thesheath (PEBAX 7233) bonded to the hypotube. Two specimens of sample Jwere tested. The average values of certain parameters determined for thespecimens of sample J are listed in Table II.

While certain embodiments have been disclosed, the invention is not solimited.

As an example, the tube-shaped catheter components can be used in anydesired medical device system, including catheters having variousdesigns, such as guide catheters, dialysis catheters (e.g., Vaxcel®chronic dialysis catheters), non-valved central venous catheters (e.g.,Vaxcel® tunneled central venous catheters), valved central venouscatheters (e.g., PASV® tunneled central venous catheters) non-valvedperipherally inserted central catheters (e.g., Vaxcel® PICC peripherallyinserted central catheters), valved peripherally inserted centralcatheters (e.g., PASV® PICC peripherally inserted central catheters, andVaxcel® PICC with PASV® valve technology) or valved ports (e.g., PASV®implantable ports) and non-valved ports (e.g., Vaxcel® standard mini andmicro implantable access systems) available from Boston Scientific Corp.(Natick, Mass.).

As another example, the tube-shaped catheter component can be used inballoon catheter systems as described above with reference to FIG. 1,but without also including a midshaft. For example, referring to FIG. 1,a similar balloon catheter can be made to balloon catheter 100 butwithout midshaft 150, by extending the length of hypotube sheath 140 tothe proximal end 172 of distal shaft 170. This could be done, forexample, without changing the length of hypotube 160 (e.g., withoutextending distal end 162 of hypotube 160). Such a balloon catheter couldpotentially offer the advantage, for example, of a reduced profile.

As a further example, the material can be used in other parts of aballoon catheter, such as, for example, to bond outer and inner tubes ofa balloon dilation catheter, to form a sheath over various components ofan infusion catheter, as part of the material of the balloon of aballoon catheter, as a sheath to connect the catheter forming portionand a hub forming portion of a catheter-hub assembly, to bond a wire toa hypotube, and/or to join two or more hypotubes (e.g., to join apolymer hypotube to a metal hypotube).

As an additional example, and as noted above, the materials andprocesses can be used in a variety of systems, including medical devicesystems and medical devices. The materials and/or processes can be usedin any system in which it is desirable to bond two or more componentstogether, particularly where it is advantageous to use relatively strongand/or thin materials to provide the bond between the components.Examples of additional systems include electrical systems (to joinelectrical components), optical systems (e.g., to join fiber opticcables), packaging, and protective covering over pipes used in flowlines.

As yet another example, a tube of a pre-stretch-blown (e.g., extruded)material and/or a tube of a stretch-blown material can have any desiredlength and/or cross-sectional shape (e.g., circular, square, triangular,rectangular). Moreover, a pre-stretch-blown (e.g., extruded) materialand/or a stretch-blown material need not be in the form of a tube. Forexample, the material(s) can be in the form of a mat or a sheet (e.g., aflat mat, a flat sheet, a partially rolled mat, a partially rolledsheet).

As an additional example, the tube-shaped catheter component can benon-polymeric. For example, the material can be nitinol, glass, or ametal or metal alloy (such as stainless steel or copper wire).

As another example, in some embodiments a catheter can be longitudinallyand/or radially stretch-blown. The catheter can be stretch-blown, forexample, to a length of from about 30 centimeters to about 180centimeters (e.g., about 100 centimeters) and/or an outer diameter offrom about 0.020 inch to about 0.180 inch (e.g., from about 0.020 inchto about 0.180 inch).

Other embodiments are within the scope of the following claims.

1. A component of a balloon catheter shaft, wherein the component of theshaft includes a region that comprises a polyamide having a hoop stressratio of at least about 1.25, wherein the region of the component istube-shaped.
 2. The component of claim 1, wherein the componentcomprises a first layer and a second layer, the first layer having adifferent flexibility from the second layer.
 3. The component of claim1, wherein the hoop stress ratio of the polyamide is at least about 1.5.4. The component of claim 1, wherein the polyamide has a tensilestrength of at least about 21,000 psi.
 5. The component of claim 1,wherein the polyamide has a hoop stress of at least about 3300 psi. 6.The component of claim 1, wherein the polyamide comprises a copolymer.7. An elongate medical device comprising: an elongate catheter shaftincluding one or more tube-shaped catheter shaft components selectedfrom the group consisting of a sheath, a hypotube, a midshaft, a distalouter tube, a distal inner tube, an outer tube, and an inner tube;wherein one or more of the tube-shaped catheter shaft components includea region that comprises a polyamide and has a hoop stress ratio of atleast about 1.25.
 8. The elongate medical device of claim 7, furtherincluding a first inflatable balloon attached to the catheter shaft. 9.The elongate medical device of claim 8, wherein the tube-shaped portioncomprises a first layer and a second layer, the first layer having adifferent flexibility from the second layer.
 10. The elongate medicaldevice of claim 8, wherein the hoop stress ratio of the polyamide is atleast about 1.5.
 11. The elongate medical device of claim 8, wherein thepolyamide has a tensile strength of at least about 21,000 psi.
 12. Theelongate medical device of claim 8, wherein the polyamide has a hoopstress of at least about 3300 psi.
 13. The elongate medical device ofclaim 8, wherein the polyamide comprises a copolymer.
 14. A component ofa catheter, comprising: an elongate shaft including a hypotube and asheath disposed on the hypotube, wherein the elongate shaft includes atube shaped region that comprises a polyamide having a hoop-stress ratioof at least about 1.25.